Process of making castings of aluminum and aluminum alloys.



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EARL BLOUGH, OF PARNASSUS, PENNSYLVANIA, ASSIGNOR TO ALUMINUM COMPANY OI AMERICA, OF PITTSBURG, PENNSYLVA NIA, A CORPORATION OF PENNSYLVANIA,

PROCESS OF MAKING CASTINGS OF ALUMINUM AND ALUMINUM ALLOYS.

Specification of Letters Patent.

Patented March 23, 1909..

Application filed November 11, 1907. Serial No. 401,736.

To all whom it may concern: Be it known that I, EARL BLOUGH, a citizen of the United States, and resident of Parnassus, Westmoreland county, and State of Pennsylvania, have made a new and useful I Invention Relating to Processes of Making Castings of Aluminum and Aluminum Alloys,

of which the following is a specification.

This invention relates to processes for cast+ ing aluminum and aluminum alloys, and res lates especiallyto recesses of casting aluminum, aluminum al oys, and so forth, in molds comprising ordinary foundry sand and ca'r-. bonaceous diflicultly oxidizable material of a dense character, the aluminum alloys bein quickly chilled and thus given increase strength and toughness by reason of the in-- creased heat conductivity of the mold caused" by the carbonaceous material. For this purpose 10 to per cent. or so of finely ground carbonaceous material maybe incorporated with ordinary foundry sand without impairing its desirable qualities in green sand molding, although, of course, the proportion of carbonaceous material'used may vary considerably. l i

The carbonaceous material is preferably I dense, difficultly oxidizable and comprises crystalline carbonaceous material so as to best give the desired increase of heat con ductivity to the mold and effect the pro or chilling of the casting. Suitable fixed t ifficultly oxidizable carbonaceous material may be prepared by finely grinding parts of cod petroleum coke and 25 parts of electric ight carbon or similar material and thorou incorporating them with 25 parts. of coa tar pitch as in a suitable kneading 'machine. The mixture may be formed-into suitable blocks under heavy pressure in any desired apparatus, such as an extrusion )rcss, and the molded pieces are then preferably thoroughly carbonized for a considerable time at high temperature. This may be readily done by packing them in a suitable electric furnace and subjecting them fortcn days or more to an intense heat greatly in excess of the heat of themetal used in the casting process. "In this we the volatile material is thoroughly expel ed and the carbon is given a very dense apparently crystalline structure so as to be a 'Very good heat conductor and dillicu'ltly oxidizablc. This material may be groundinany way to the desired fineness which should ap- 5 proximate that of the sand with which it is W hen 15-%. or so by volume of this fine fixed carbonaceous material is thoroughly incorporated with ordinary foundry sand the. bonding properties of the sand are substantially unimpaired and green sand molds may be made with the same facility as where or jdinary' foundry sand alone is employed.

When such molds are poured inthe casting of aluminum alloys the metal in contact with the face of the mold is suddenly chilled by reason of the increased conductivity of the mold caused by this highly conductive carbonaceous material and the castings are given a finely crystalline structure and a very considerable increase in tensile strength. Vt 1th an ordinary aluminum alloy contalnmg about 8 of copper the tensile strength is in v clreasedfrom 1 5% to 25% in this manner. The castlngs have the sa-me'soundness as castings formedln ordinary sandmolds, since the venting qualities of the sand are unimpaired by the incorporation of such carbonaceous material which also because of its fixed character does not cause blowing by the evolution of any-gaseous material when the hot metal comes into contact therewith.

Molds made of this material can be dumped and the sand riddled without difficulty, and

as the carbonaceous material is not readily oxidizable the sand may be usedrepeatedly without special. treatment and without substantial diminution of its valuable chilling properties, only needing to be sufficiently dampened or tempered before being forced into the flasks'to form molds in the ordinary green sand molding )rocess. The ingredients specified in the i ustrative composition may be replaced in whole or in part by other carbomtceous material, preferably. of a dense or crystalline character and having the other proierties referred to. i

aving described this invention in connection with illustrative com ositions and methods of procedure, to the etails of which disclosure the invention is not, of course, to be limited, what is claimed 'as new and hat is v 1 desired to be secured by Letters Patent isset forth in the appended claims.-

1. The process of making castingsof aluit minum alloys which consists in forming a green sand mold from ordinary foundry sand minum al oys which consists in forming a mold from ordinary foundry sand with which a considerable proportion of finely ground, dense, carbonaceous material, substantially fixed at the heat of the molten metal used,

has been incorporated without destroying the bonding properties of the sand and in casting the metal into said mold thus quickly chilling the metal and strengthening the casting by the increased heat conductivity of the mold.

3. The rocess of making castings of aluminum a oys which consists in forming a green sand mold from ordinary foundry sand with which a considerable proportion of carbonaceous material, substantiall fixed at the heat of the molten metal used: has been incorporated. without destro ing the bonding properties of the sand am in casting the metal into said mold thus quickly chilling the metal and strengthening the casting by the increased heat conductivity of the mold.

4. The process of making castings which consists in forming a green sand mold from sand with which a considerable proportion. 01' finely ground, carbonaceous material has been incorporated and in casting the metal into said mold, thus'quickly chilling the metal and strengthening the casting by the increased heat comluctivity ol' the mold.

5. The process of making castings comprising a large proportion of aluminum which consists in forming a green sand mold l'rom sand with which a considerable proportion of finely round, heat conductive, dillic-ultly oxidiza le, carbonaceous material substantially fixed at the heat of the molten metal used has been incor orated and in casting the metal into such mo ld thus strengthening the casting by the increased chilling action of the mold.

6. The )I'OCGSS oi making castings ol' aluminum alloys which consists in forming a green sand mold from ordinary foundry sand with which less than 25% of finely ground, difficultly oxidizable, carbonaceous material substantially fixed at the heat of the molten metal used has been incorporated without destroying the bonding properties 01' the sand and in casting the metal into said mold thus strengthening the casting by the increased chilling action of the mold.

7. The process of making castings com n'ising a'large roportion of aluminum which consists in orming a green sand mold of material comprising less than 25% ol linely ground, dif'licultly oxidi'zable, inert, highly heat-conductive material and in casting the metal into said mold thus strengthening the casting by the increased chilling action 01' the mold, said mold being substantially free from carbonaceous material volatile at the h rat ol' the metal used.

EARL BLOUGll.

\Yitnesses E. l). CREE, J. L. MOLAMM N. 

